Permanent magnet arrangement, axial flux machine and electromechanical drive

Abstract

The invention relates to a permanent magnet arrangement (1) for use as a rotor or stator of an axial flux machine (10), in particular an axial flux machine (10) of a door drive. The permanent magnet arrangement (1) comprises several permanent magnets (3) arranged in a ring around a central axis (2) and each magnetized in an axial direction parallel to the central axis (2). Adjacent permanent magnets (3) have opposite polarities. All permanent magnets (3) are integrally formed and constitute a multi-pole-pair ring magnet.

Description

[0001] The invention relates to a permanent magnet arrangement for use as a rotor or stator of an axial flux machine, in particular an axial flux machine of a door drive. The permanent magnet arrangement comprises a plurality of permanent magnets arranged in a ring around a central axis and each magnetized in an axial direction parallel to the central axis. Permanent magnets arranged adjacent to one another each have opposite polarity. The invention also relates to an axial flux machine with a coil arrangement and a permanent magnet arrangement, as well as to an electromechanical drive.

[0002] The use of axial flux machines, and in particular brushless axial flux machines, for door drives is known from the prior art and is described, for example, in document EP 3 974 610 A1. In such axial flux machines, the magnetic flux flows through the permanent magnet arrangement and the coil arrangement axially to the rotational axis of the motor, which forms the machine axis. The permanent magnet arrangement forms part of a stator of the axial flux machine, and the coil arrangement forms part of a rotor of the axial flux machine, or the permanent magnet arrangement forms part of the rotor of the axial flux machine, and the coil arrangement forms part of the stator of the axial flux machine. The permanent magnets of the permanent magnet arrangement and coils of the coil arrangement are usually arranged in a ring around the machine axis.The permanent magnets are aligned so that one of the poles of each permanent magnet is closer to the coil arrangement than the other pole, so that magnetic field lines running between the north pole and the south pole within the respective permanent magnet run parallel to the machine axis. The permanent magnets usually have an approximately trapezoidal base, with the dimensions of the base being a multiple of the height of the respective permanent magnet. Straight lines through side edges of the base usually run through a point on the axis of rotation or the machine axis, so that an inner edge of the base is shorter than an outer edge of the base. The permanent magnets therefore have the shape of an approximately trapezoidal prism. The inner and outer edges are often also shaped like segments of a circle, so that the base forms a ring segment.

[0003] To manufacture the permanent magnet arrays known from the prior art, individual permanent magnets of the permanent magnet array are typically aligned on a carrier plate and attached to the carrier plate, for example, by adhesive. The height of the permanent magnet array corresponds to the height of the carrier plate plus the height of the permanent magnets.

[0004] The object of the invention is to improve the permanent magnet arrangements known from the prior art.

[0005] This object is achieved according to the invention in that at least two permanent magnets arranged adjacent to one another are designed as a single piece. In this way, the effort required to manufacture the permanent magnet arrangements can be reduced, since fewer individual permanent magnets need to be applied to the carrier plate. Several permanent magnets can be designed as a single piece by using a powder metallurgy process for production, wherein a weak magnetic field is applied simultaneously during the pressing of the powdered starting material, thereby prescribing a preferential polarization that is usually defined radially or axially. The blanks produced in this way are then magnetized in a magnetization device by strong magnetic fields of different or opposite polarization in adjacent regions of the blank.This different polarization is reproduced by the powder particles of the starting material and frozen or stored in the resulting magnetic material.

[0006] In order to further reduce the manufacturing effort for the permanent magnet arrangement, the invention provides that all permanent magnets are designed as a single piece and form a multi-pole pair ring magnet. The design as a multi-pole pair ring magnet offers the additional advantage, when used according to the invention as a permanent magnet arrangement for a stator or rotor of an axial flux machine, that the carrier plate can be omitted if necessary, so that less installation space is required for the stator or rotor. Furthermore, the permanent magnet arrangement in this design can advantageously have continuously flat surfaces or side faces, which, for example, when used as a rotor, achieves more uniform running. In the design with continuously flat surfaces, the individual permanent magnets can no longer be visually distinguished from one another.Therefore, within the meaning of this invention, the various permanent magnets of the permanent magnet arrangement are differentiated from one another by the fact that the direction of the magnetic flux density generated by the permanent magnet arrangement is reversed between two adjacently arranged permanent magnets. The shape of the permanent magnets is determined by the magnetic flux density generated by the permanent magnet within the ring magnet, which decreases to zero at the sides of the respective permanent magnet, with the side surfaces of the permanent magnet being predetermined by this decrease to zero. The top and bottom surfaces of the respective permanent magnets are determined by the top and bottom surfaces of the ring magnet.

[0007] Advantageously, the invention provides for a demagnetized region to be provided between each two adjacent permanent magnets, with the demagnetized region being integrally formed with the permanent magnets. This simplifies the manufacturing process for the integrally manufactured permanent magnets, since the external magnetic fields applied during magnetization do not have to be applied directly adjacent to the starting material.

[0008] In a particularly advantageous embodiment of the permanent magnet arrangement according to the invention, a base surface of the permanent magnets has permanent magnet edges that extend obliquely to one another. In this way, particularly with an annular design of the permanent magnet arrangement, the available magnetizable starting material can be magnetized to the greatest possible extent, so that a comparatively high magnetic flux density can be provided in the smallest possible area. A base surface of the permanent magnets can, for example, be approximately trapezoidal, with the inner and outer sides of the permanent magnets being curved and following the annular shape of the permanent magnet arrangement.As already explained above, the permanent magnet edges are determined by the magnetic flux density generated within the ring magnet by the permanent magnet and which drops to zero on the sides of the respective permanent magnet, whereby the side surfaces of the permanent magnet or the permanent magnet edges are predetermined by this drop to zero.

[0009] Advantageously, the invention provides that the permanent magnet edges have a curvature that continuously increases from an inner side facing the central axis to an outer side facing away from the central axis. It is known that so-called cogging forces or cogging moments occur during operation of axial flux machines, which lead to increased noise and vibration during operation and reduce the overall efficiency of the machine. The cogging forces are magnetic interference forces and arise from interactions between the permanent magnets and coil cores or stator teeth, which are made of iron or another material with good magnetic conductivity. Various measures are known from the prior art to reduce these cogging forces.

[0010] One of these measures is the so-called "beveling of the magnetic edges" of the permanent magnets. In this measure, the permanent magnets are adjusted, starting from their approximately trapezoidal base, so that the straight lines through the side edges no longer run through the rotation axis, or by choosing shapes that deviate from the trapezoidal shape, for example, with bent side edges. One known option for beveling the magnetic edges is to adjust the permanent magnets, starting from their trapezoidal base, so that the side edges are tilted by a so-called bevel angle relative to the straight lines running through the rotation axis. The side edges of the permanent magnets exhibit the same displacement angle for each connection point on the respective side edge, or at least for each connection point on sections of the side edges if the side edge is bent.This is also called the helix angle.

[0011] Tests with conventional permanent magnets with an approximately trapezoidal base area and inner and outer edges shaped like circular segments have shown that the contribution of individual sections of the permanent magnets to the cogging forces generated by these permanent magnets depends on the distance of the respective section from a machine axis or central axis of the axial flux machine. The inventive design of the permanent magnet edges exploits this knowledge to further reduce the cogging forces. For this purpose, instead of the design with a constant displacement or helix angle, the base area of ​​the permanent magnet or the permanent magnet edges are designed such that the opposite side surfaces have a continuously increasing or decreasing helix angle, with the helix angles being larger or smaller.are smaller, the greater the distance of the respective section of the permanent magnet from the machine axis and whereby the respective helix angle increases or decreases disproportionately depending on this distance.

[0012] Advantageously, the invention provides for the permanent magnet arrangement to be made of a rare earth material. Advantageously, the material used can be, for example, neodymium-iron-boron or samarium-cobalt.

[0013] To protect the permanent magnet arrangement during operation of the axial flux machine, the invention provides for the permanent magnet arrangement to have a coating to protect the permanent magnets. The coating can advantageously be a nickel-copper-nickel coating, for example. According to the invention, this coating is only a few micrometers thick, and advantageously less than 12 micrometers thick.

[0014] In order to improve the running properties of the axial flux machine when using the permanent magnet arrangement according to the invention, the invention provides that the permanent magnet arrangement has eight permanent magnets, advantageously twelve permanent magnets and particularly advantageously sixteen permanent magnets.

[0015] Advantageously, the invention provides that the ratio of a diameter of the permanent magnet arrangement to a thickness of the permanent magnet arrangement in the axial direction is at least twenty, advantageously at least thirty, and particularly advantageously at least thirty-six. Such a configuration allows the permanent magnet arrangement to be particularly flat, so that the installation space required for arranging the permanent magnet arrangement in the axial flux machine can be reduced. Advantageously, for a permanent magnet arrangement with a diameter of 40 to 120 mm, a thickness of <1.1 to 6 mm is provided.

[0016] The invention also relates to an axial flux machine with a coil arrangement and a permanent magnet arrangement as described above, wherein the coil arrangement comprises a plurality of electrical machine coils arranged adjacent to one another in a ring around the machine axis, wherein the coil arrangement is arranged axially displaced adjacent to the permanent magnet arrangement. Advantageously, the axial flux machine is a brushless axial flux machine. Such axial flux machines are particularly well suited for use with door or window drives.

[0017] Advantageously, the invention provides that the inner ring circumference and the outer ring circumference of the permanent magnet arrangement essentially correspond to corresponding ring circumferences of the coil arrangement. This allows a particularly compact design of the axial flux machine to be achieved.

[0018] The invention also relates to an electromechanical drive for actuating a wing mounted rotatably and / or displaceably on a structural element, in particular a door wing or a window wing, with an axial flux machine as described above

[0019] Advantageously, the invention provides that the electromechanical drive is a swing door, sliding door or revolving door drive.

[0020] Further advantageous embodiments of the method according to the invention and of the electromechanical drive according to the invention are explained in more detail with reference to exemplary embodiments shown in the drawing.

[0021] It shows: Figures 1a and 1b schematically illustrated views of a permanent magnet arrangement according to the invention and Figure 2a schematically illustrated sectional view of an electromechanical drive in which the permanent magnet arrangement according to the invention is used.

[0022] Figure 1a shows a schematic plan view and Figure 1b A schematic side view of a permanent magnet arrangement 1 for use as a rotor or stator of an axial flux machine. The permanent magnet arrangement 1 has a plurality of permanent magnets 3 arranged in a ring around a central axis 2 and each magnetized in an axial direction parallel to the central axis 2. A non-magnetized region 4 is provided between each two adjacent permanent magnets 3, the non-magnetized region 4 being formed integrally with the permanent magnets 3. In the drawing, two permanent magnets 3 and two non-magnetized regions 4 are identified by a reference numeral as examples.

[0023] Permanent magnets 3 arranged adjacent to each other each have an opposite polarization. This is Figure 1a marked by the letters "N" for magnetic north pole and "S" for magnetic south pole. All permanent magnets 3 are integrally formed, thus forming a multi-pole pair ring magnet.

[0024] A base surface 5 of the permanent magnets 3 has permanent magnet edges 6 that extend obliquely to one another. In the drawing, a base surface 5 with two permanent magnet edges 6 is identified by a reference symbol.

[0025] A diameter 7 of the permanent magnet arrangement 1 is between 40 and 120 mm. A thickness 8 of the permanent magnet arrangement 1 in the axial direction is between <1.1 and 6 mm. The ratio between diameter 7 and thickness 8 is approximately 36. The permanent magnet arrangement 1 also has continuously flat surfaces 9.

[0026] In Figure 2 A schematic sectional view of an electromechanical drive 10 for actuating a leaf, in particular a door leaf or a window leaf, which is rotatably and / or displaceably mounted on a structural element is shown. The electromechanical drive 10 has an axial flux machine 11, which has a permanent magnet arrangement according to the invention (not shown) as a rotor. A drive shaft 12 of the axial flux machine 11 is operatively connected to the leaf (not shown) via a power transmission device 13. The power transmission device 13 essentially consists of a gear 14 connected to the axial flux machine 11 and a lever 15. This converts a movement of the drive shaft 12 into a movement of the leaf.

[0027] Figure 3shows a schematic plan view of a permanent magnet arrangement 1 for use as a rotor or stator of an axial flux machine. The permanent magnet arrangement 1 has a plurality of permanent magnets 3 arranged in a ring around a central axis 2 and each magnetized in an axial direction parallel to the central axis 2. A non-magnetized region 4 is provided between each two adjacent permanent magnets 3, the non-magnetized region 4 being formed integrally with the permanent magnets 3. In the drawing, three permanent magnets 3 and two non-magnetized regions 4 are identified by a reference numeral as examples.

[0028] Permanent magnets 3 arranged adjacent to one another each have opposite polarity. All permanent magnets 3 are integrally formed with one another, thus forming a multi-pole pair ring magnet.

[0029] A base surface 5 of the permanent magnets 3 has permanent magnet edges 6 extending obliquely to one another, wherein the permanent magnet edges 6 have a curvature that continuously increases from an inner side 16 facing the central axis 2 to an outer side 17 facing away from the central axis 2. In the drawing, a base surface 5 with two permanent magnet edges 6 is identified by a reference symbol as an example.

Claims

1. Permanent magnet arrangement (1) for use as a rotor or stator of an axial flux machine (10), in particular an axial flux machine (10) of a door drive, wherein the permanent magnet arrangement (1) has a plurality of permanent magnets (3) arranged in a ring around a central axis (2) and each magnetized in an axial direction parallel to the central axis (2), and wherein permanent magnets (3) arranged adjacent to one another each have an opposite polarization, characterized in that at least two permanent magnets (3) arranged adjacent to one another are designed in one piece.

2. Permanent magnet arrangement (1) according to claim 1, characterized in that all permanent magnets (3) are designed in one piece with each other and form a multi-pole pair ring magnet.

3. Permanent magnet arrangement (1) according to claim 1 or claim 2, characterized in thatan unmagnetized region (4) is provided between each two permanent magnets (3) arranged adjacent to one another, the unmagnetized region (4) being designed in one piece with the permanent magnets (3).

4. Permanent magnet arrangement (1) according to one of the preceding claims, characterized in that a base surface (5) of the permanent magnets (3) has permanent magnet edges (6) running obliquely to one another.

5. Permanent magnet arrangement (1) according to claim 4, characterized in that the permanent magnet edges (6) have a curvature that increases continuously from an inner side (16) facing the central axis (2) to an outer side (17) facing away from the central axis (2).

7. Permanent magnet arrangement (1) according to one of the preceding claims, characterized in that the permanent magnet arrangement (1) is made of a rare earth material. 8.Permanent magnet arrangement (1) according to one of the preceding claims, characterized in that the permanent magnet arrangement (1) has a coating to protect the permanent magnets (3).

9. Permanent magnet arrangement (1) according to one of the preceding claims, characterized in that the permanent magnet arrangement (1) has eight permanent magnets (3), advantageously twelve permanent magnets (3) and particularly advantageously sixteen permanent magnets (3).

10. Permanent magnet arrangement (1) according to one of the preceding claims, characterized in that a ratio of a diameter (7) of the permanent magnet arrangement (1) to a thickness (8) of the permanent magnet arrangement (1) in the axial direction is at least twenty, advantageously at least thirty and particularly advantageously at least thirty-six. 11.Axial flux machine (10) with a coil arrangement and a permanent magnet arrangement (1) according to one of the preceding claims, wherein the coil arrangement has a plurality of electrical machine coils arranged adjacent to one another in a ring shape around the machine axis, wherein the coil arrangement is arranged axially displaced adjacent to the permanent magnet arrangement (1).

12. Electromechanical drive for actuating a wing rotatably and / or displaceably mounted on a structural element, in particular a door wing or a window wing, with an axial flux machine (10) according to claim 11.

13. Electromechanical drive according to claim 12, characterized in that the electromechanical drive is a swing door, sliding door or revolving door drive.

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